Pick up for torque-measuring apparatus



March 5, 196 3 K. MOSWALD PICK up FOR TORQUE-MEASURING APPARATUS 6Sheets-Sheet 1 Filed Sept. 15, 1958 March 5, 1963 K. OSWALD 3,079,791

7 PICK UP FOR TORQUEMEASURING APPARATUS Filed Sept. 15, 1958 sSheets-Sheet 2 Fig.4

March 5, 1963 K. OSWALD 3,079,791

PICK UP FOR TORQUE-MEASURING APPARATUS I Filed Sept. 15, 1958 eSheets-Sheet a March 5, 1963 K. OSWALD 3,079,791

PICK UP FOR TORQUE'MEASURING APPARATUS Filed Sept. 15, 1958 eSheets-Sheet 4 Fig.9

4 l l I I 1 ns 33 l W A i if CI 30 34 L March 5, 1963 K. OSWALD PICK UPFOR TORQUEMEASURING APPARATUS Filed Sept. 15, 1958 6 Sheets-Sheet 5March 5, 1963 K. OSWALD 3,079,791

' PICK UP FOR TORQUE-MEASURING APPARATUS Filed Sept. 15, 1958 eSheets-Sheet e PHIK UP FUR TGRQUE-MEASUREQG APPARATUS; Karl Oswald,Sari-zen, Switzerland, nssignor to G. A.

Messen-Jasehin, Sarnen, Switzerland, a corporation of Switzerland FiledSept. 15, F958, Ser. No. 76%,94? Claims priority, applicationdwitzerland Sept. 14-, 1%? 11 Claims. (Cl. 73-136) The invention relatesto a transmitter or pick-up for a torque-measuring instrument, thetransmitter or pickup having toothed rims which are secured at spacedpositions to a shaft, the torque of which is to be measured. The rimsare co-axial with the shaft and they co-operate With a stator to bringabout, in the case of each toothed rim, a cyclic variation in someelectrical parameter. The two cyclic variations are compared in furtherapparatus which gives an indication of the torque on the shaft. This mayinvolve supplying to an indicator two cyclically varying voltages,induced in two dilferent magnetic fields, and having an indicator whichgives a torque indication in dependence upon the phase differencebetween the two voltages.

In known pick-ups of this type, each toothed-rim carrier is mounted onthe shaft by means of a cylindrical or conical surface. Due to the axialextent of this surface, which in practice cannot be brought to bearcompletely against the cooperating surface of the shaft, the exactextent of the measuring section, i.e. the axial distance apart of thesupporting positions of the two toothed rims on the shaft, is unknown,which may result in errors of measurement. Furthermore, in the knownpick-ups, the stator is supported independently of the two toothed rims.The often unavoidable eccentricity of the toothed rims with respect tothe shaft axis results in a variation of the distance of the toothedrims from the stator parts influenced by them during a revolution of theshaft, which likewise leads to errors of measurement.

in the pick-up according to the invention, these disadvantages areavoided. For this purpose, the pickup according to the inventioncomprising a shaft, first and second toothed rims co-axial with theshaft, first and second cylindrical support members surrounding theshaft and to which the first and second toothed rims, respectively, arefixed, first and second fixing means secured to the first and secondsupport members, respectively, and making substantially line contactwith the shaft around first and second spaced peripheral lines on theshaft, whereby the first and second rims will turn in accordance withthe turning of the shaft at said first and second lines, respectively, astator adjacent the toothed rims, magnetic means in the stator forco-operating with the teeth for the generation of alternating currentwhen the shaft turns, and bearings engaging the stator and one of thesupport members at spaced locations distributed around the entirecircumference of said one support member and supporting the stator inspace and locating it both axially and radially with respect to said onesupport member.

Since the toothed rims are each connected to the shaft only on acircular, i.e. peripheral, line on the latter, the length of themeasuring section situated between these two peripheral lines is exactlydeterminable. Measuring errors due to eccentric mounting of the toothedrims on the shaft cannot occur, since the stator is mounted on one ofthe toothed rim supports itself.

In the constructions of torque pick-ups known heretofore, thearrangement is always such that the pick-up rotor runs in the stator.Such an arrangement, however, is n ot always ree from transmissionerrors, and results in such errors even if the two transmissionelements, namely the rotor toothed rims and the pick-up magnet systemson the stator lie very close together. In order to avoid the above-Federated Perla-r. E3, 1983 ice mentioned technical drawbacks, it ispossible in a special embodiment to construct a pick-up in which thestator, independently of the rotor formed by the toothed rims, ispressed resiliently against the running surfaces of the rotor, so thatthe distance between the magnet poles of the magnet systems mounted onthe stator and the toothed rims is maintained constant as the rotorturns.

Constructional examples of the subject of the invention are representedin the accompanying drawings, wherein:

FIGURE 1 shows a part of an axial section through a pick-up,

FIGURE 2 a detail of the pick-up in an axial section offset relativelyto the section according to FIGURE 1,

FIGURE 3 a detail of FIGURE 1 in end view,

FIGURE 4 a part of the stator of FIGURE 1 in end view,

FIGURE 4:: a part of a radial section through an alternative form ofpick-up rotor,

FIGURE 5 a part of an axial section through a second example of thepick-up according to the invention,

FIGURE 6 an end view of the pick-up according to FIGURE 5 on a smallerscale,

FIGURE 7 a detail of FIGURE 5 in plan on a larger scale,

FIGURE 8 a third example of a pick-up according to the invention in endview,

FEGURE 9 an wial section analogous to FIGURE 5 through a fourth exampleof a pick-up according to the invention,

FIGURE 10 an axial section of a pick-up according to the invention witha first example of a device for zeropoint calibration,

FIGURES 11 and 12 in side view and end view, respectively, the pick-upwith a second example of a device for zero-point calibration, and

FIGURES l3 and 14 in side view and end view the pick-up with a thirdexample of a device for zero-point calibration.

in FIGURES 1-4 of the drawings, the torque on a shaft 1 is to bemeasured by reference to the amount by which one end of a test section aof the shaft turns relative to the other end. Mounted on said shit 1, ata small distance apart within the measuring section a are two toothedrims 2 and 3, the teeth of which are of equal pitch and of magneticmaterial. The toothed rim 2 is formed as end flange of a cylindricalsupport 4-, which is mounted co-axially and with radial spacingrelatively to the shaft 1. The end of the support 4 carrying the toothedrim 2 is supported on the shaft 1 by means of a ring 5 mounted on theshaft so as to turn relative to the shaft. The other end of the support4 is held by a ring the inner edge of which remote from the support 4 isbevelled. This bevelling and the adjacent end face of a clamping ring 7partly define an annular recess between the two rings 6 and 7 and theshaft 1, in which ecess lies a ring 3 of round wire. By means of screws,not shown, the clamping ring 7 is fixed to the ring 6, the wire ring 8being pressed against the shaft 1. The

wire ring 3 makes line contact with the shaft at the peripheral line onthe shaft 1 representing one boundary of the measuring section a, andagainst said shaft, so that the support aand with it the toothed rim 2is firmly connected to the shaft 1 at the desired position. The secondtoothed rim 3 is connected to one end of a cylindrical shell 9,surrounding the shaft 1 with radial spacing and co-axially, the otherend of said shell being fixed to the external periphery of an annulardisc 10 coaxial with the shaft l. The annular disc 19 is anchored by itsinner edge to a ring 11, the inner edge of which, remote from the disc,is bevelled. By means of screws, not shown, a clamping ring 12 is fixedto the ring 11, and together with the bevelling on the ring 11 partlydefines an anul'ar recess facing the shaft 1. In this recess lies a ring13 of round wire, which like the wire ring 8, is pressed on the shaft 1along a peripheral line on the latter, representing the correspondinglimit of the measuring section a, and thus connects the support 9, withits toothed rim 3 firmly to the shaft at the desiredposition. Mountedinthe toothed rim 2 at intervals apart on the circle are bushes 14, eachof which has an end part which is eccentric relative to the bush axisand which carries a ball bearing 15.

On the external periphery of the support 40f the toothed rim 2 aresupported a plurality of ball bearings 16, axially parallel to the shaftaxis ar d each mounted on "an eccentric end part of a bush 17. Thebushes 17 are mounted in a stator disc 18 and can be swung about p v xeo a m (F E .3) fo ra a a u ment of the bearings 16. The arms 19arepermanently carried by the stator disc. The stator disc 18, supportedradially on the support 4 by means of the bearings 16 s p e t fr ota y mn .B ZY I WR Su means may take a form -similarto;-that described belowand illustrated in FIGURE 6. The stator disc 18 is provided withdetachable cover plates 20 andZl. In an inner flange 22 (FIGURE 2) ofthe stator disc 18, v coaxial with the shaft, rotatably adjustablepivots 2} are mounted between the bearings 16, the end parts of whichpivots, projecting towards the shaft 1 from the flange 22..are eccentricand each carry a ball'bearing 24. The outer rings of said bearings bearagainst a radial surface on the support 4, so that by means of saidbearings 24, the stator is supported axially on the support 4. l

Magnet systems A -A (FIGURE 1) with pole shoes 26 and induction coils 27are provided at equal intervals apart on a circle,the pole shoes- 26facing the periphery of the toothed rim 2. Between the magnet systems AA fourv magnet systems 13 -13 with pole shoes 28 and induction coils 29are provided, the pole shoes 28 facing the periphery of the. toothed rim3. Between the magnet systems A; and B; there isprovided an identic-a1magnet system C with pole shoes facing 'one of the toothed rims, whilebetween the magnet systems A and B is mounted afurther magnet system Dwith pole shoes facing the other toothed rim. The arrangement of themagnet systems on the disc 18 or ping 2'5 is indicated in FIGURE 4. Themagnet systems A to A and C and D arefixed on the stator disc '18 bymeans of bolts passing through round holes in the stator discand-through arcuate slots in a ring which islet into a recess in thestator ,disc. The remaining magnet systems are fixed on the ring 25which can be turned about its axis, as far as permitted by the ends ofthe arcuate slots, in order to adjust the positions of the magnetsystems A to A and C and D relative to the other magnet systems. Themagnet systems A, and C, as well as A and D serve for calibration andChecking of the measuring instrument. Since the angular. positions,around the ring 25, of the magnet systems A and C, for example, areaccurately known, then it is known what the phase difference between thepotentials from these two magnet systems really is. It is suflicient,then, to apply the two potentials to the measuringinstrument, whichgives anindicati-on of the phase difference. If the indicated phasedifference is not the same as the accurately known phase difference, theamplification of the potentials by the instrument requires adjustmentuntil exact correspondence is obtained. The magnet systems A A and 3 -13serve for torque indioation.

Tne two toothed rims land-3 are made by screwing their blanks togetherand machining them simultaneous iv. The support 4 is machinedat the sametime so that accurate round running of 'the ball bearings 16 withrespect to the surface of the supportupon which they bear is ensured.The toothed rims remain screwed together until after their assembly inthe pick-up and fixing of the toothed rim 3 to its support 9, 10.

The ball bearings 16 and 24', like the ring 25 carrying the magnetsystems B -B are adjusted before the ap plication of the cover plates20, 21. The magnet systems li -B are adjusted so that for zero torque adesired phase displacement is adjusted, for which the measuringinstrument, not shown, indicates zero.

In the operation of the pick-up, due to the twisting of the measuringsection a or of the toothed rims 2 and 3,

occurring during the rotation of the loaded shaft 1, cyclic variationtakes place of the magnetic field of the magnet systems of the stator,whereby corresponding alternating voltages are generated in the coils 27and 29. The phase difference between the voltages is used for indicatingthe torque efiective on the shaft 1.

In the example described, the supports of the toothed mims 2 and 3 areclamped on the measuring shaft 1' by means of wire rings 8 and 13 whichdo not, in fact, follow a complete circle but are split, like pistonrings. It is evident that instead of rings of round wire, ringswedge-shaped in cross-section or individual 'balls distributed aroundthe periphery of the shaft couldbeused; In the exampleshown, themagnetic flux in. the magnet systems is varied cyclically for.generating the desired al ternating voltages; similarly, however, themagnitudeof another electrical parameter (for example inductance orcapacitance) could be .varied cyclically by the relative movementbetween stator and toothed rims.

As shown in FIGURE 40, instead of providing salient teeth on the rotor,.the parts 2 and 3 may be formed with blindbores 2A of equal depth,diameter and spacing, so that the rotor parts between the teethsimulate. salient teeth. s 1

In the example according to FIGURES S to 7, 30 is the measuring shaftwith test section a. Two toothed rims 31 and 32 are mounted on said.shaft 30 at a short distance apart. Thevtoothed rim 31 is formed as endflange of a cylindrical support 33, which isimounted coaxially and witha radial spacing relative to shaft'fitl. One end of the support 33 isfixed on shaft 31) by means of a clamping ring 34 of round wire. Thewire ring 34 makes line contact with the shaft at a peripheral 'line onshaft 30 so that the support 33 and with it the toothed rim 3-1 can berigidlyconnected to the shaft 3% atthe desired position, i.e. at the endof the measuring section a. The

second toothed rim 32- is secured to. one end of a cylindrical shell 35,surrounding the shaft 3% with radial spacing and co-axially, the otherend of said shell being secured'to the external periphery of an annulardisc 36 co-axial with the shaftEil. The annular disc'36 is fixed .to theshaft 30 by means of a clamping ring 37 of round wire like the support33 around a peripheral line on said shaft representing the correspondinglimit of the measuring section a; thus the support 3'5, 36 withpitstoothed nim 32 is rigidly connected to the shaft 36 at the desiredposition. Mounted in the toothed rim 31, spaced apart on a circle, arepins 38 (FIGURE 5 only one visible). The end part of each pin projectingfrom the toothed rim 31 is eccentric relatively to the pin axis andcarries a ball bearing 39. The toothed rim 32 fixed to the shell 35- ismounted on said ball bearings 39. The eccentric pin 38 permitsadjustment of the bearings 39 in the radial direction. t

The two toothed rims 31 and 32 are each provided on their periphery witha cylindrical bearing surface 41) of the same diameter; a furtherbearing surface 41, situated in a plane at right-angles to the shaftaxisis also provided on each-of the'end sides, facing away from each other,of the two toothed rims 3i and 32. A segment-shaped stator carriage $3is mounted by means of ball bearings 42 on said bearing surfaces 49, 41of thetwo toothed rims 31, 32. In the radial direction, the statorcarriage 43 is pressed against the bearing surfaces 40 by means of aresilient system 44a (e.g. suitable springs), which is supported at afixed point, situated outside the pick-1p so that any play betweenbearing rollers and cylindrical bearing surface is avoided. In the axialdirection, each of the two ball bearings 4-2, running on the bearingsurface 41 of the toothed rim 31, is pressed against the hearing surface41 of the toothed rim 31 by means of a spring 44b (FIGURE 7), supportedon the carriage 43 itself and engaging a pivotal arm 4-5 carrying theball bearing. The carriage 43 carries the magnet systems 46, the magnetpoles 47 of which stand opposite the toothed rims 3i and 32.

If, due to a displacement of the middle of the shaft 353 or tonon-circularity, produced for example by clamping of the toothed rims,the two rotor toothed rims 3f, 32 run eccentrically, the carriage 43adapts itself to these movements, so that the pick-up gap between thetoothed rims and the magnet poles remains constant and no fluctuationscan occur in the transmitted measured values. The only condition whichmust be made from the manufacturing side is that the two cylindricalbearing surfaces 443 must be absolutely parallel to each other. This canbe obtained, however, without trouble in manufacture by machining dietwo surfaces together in one clamp on the lathe. The arrangementdescribed makes it possible to manage with one set of magnet systems; atthe s .e time, by the incorporation of an adjusting system 48 (FIGURE6), consisting of screwthreaded posts 48A and 5-313 pivotally connectedto the stator and a fixed support 48D, respectively and provided withleft and right hand threads, respectively, in combination with aturnbuckle The latter can be turned to effect movement of the carriagearound the rotor, whereby it is possible to obtain a zero-pointadjustment. When the turnbuckle is not being turned, the posts 48A and48B prevent the stator from turning around the axis of the rotor.Similar or comparable means may be provided in the other en bodiments toadjust the position of the stator and to prevent from rotating once ithas been adjusted.

For a so-called internal compensation of transmission errors, it hasbeen found to be particularly advantageous, instead of a singletransmission magnet system, to arrange three or more such systems aroundthe periphery of the pick-up rotor. Such an arrangement is shown inFIGURE 8, in which the construction of the individual stator carriages43 is the same as in the example last described. in the arrangement asshown in FEGURE 8, the three carriages 43 are so arranged that they canbe moved in the radial direction, while remaining constant relatively toeach other in th lr segmental or angular spacing 06. For this purpose,the guiding of the carriages 43 is effected by means of bolts 49 runningin radial slots. For zero-point adiustment, the stator ring db carryingthe radially slidable carriages 43 with the magnet systems can be turnedabout the center P. F1. ing of the stator ring 5% is effected by meansof clamping slit 52 co-operating with an eccentric 51..

in other respects, the construction according to PEG- URE 8 correspondsto that according to FEGURES 5-7, exce t that here instead of a singlespring 44a for pressing the individual carriages 43 against theirbearing surfaces it), two such springs re provided.

A further example is shown in FIGURE 9. Here again, the supports 33 and35', 36 of the toothed rims 31 and 32 are fixed on the shaft 30 by meansof clamping rings 34 and 37, respectively. Contrary to the previouslydescribed examples, however, in this case there is provided on eachtoothed rim only one conical bearing surface 5'3, upon which act ballbearings 54 mounted on the stator carriage 55. in this case also, thestator carriage is pressed resiliently against its bearing surfaces onthe rotor by means of a spring system, not shown, supporte outside thepick-up. instead of the supporting bearings 39 of the example firstdescribed, in this case a wire ball bearing 56 is provided between thetwo toothed rims 31 and 3M.

in the arrangement of a stator supported resiliently against the rotor,it is not absolutely essential for the two pick-up toothed rims 3?. and32 to be mounted at the smallest possible distances apart. The pick-uptoothed rim 33 may be arranged at the distance a from the pick-uptoothed 'im 32, in which case the shell tube 35 may be omitted; i.e. twomechanically independent pickup and receiving systems may be mounted onthe torquetransmitting shaft 3%. in this case, therefore, one or morestator carriages each associated with both toothed rims, are notprovided, but one or more separate carriages are provided for eachtoothed rim.

in the transmission of torque and power via shaftlines, two differentprinciples may be used for their measurement. The first principle isbased on the fact that the twisting of the shaft occurring in thetransmission of torque and power is taken as a measure of the powertransmission. The second method is based substantially on the fact thatstrain gauge strips are applied to the surface of the transmissionshaft, and these strips lengthen or shorten during the twisting of thepowertransmitting shaft in accordance with the geometrical angle oftwist. The changes in length are so vetted into voltage variations andthese voltage variations are fed to the indicating instrument by meansof a slip-ring system and suitable electrical transmission. Common toboth principles is the need for a satisfactory so-called zeropointdetermination, i.e. adjustment of the measuring instruments to thecondition of freedom of the transmission shaft from torque. Thisrequirement first of all assumes that the transmission shaft has nofrictional torque, appearing as pre-stress in the transmission shaft andproduced by starting up, for example, of a ships engine. That is to say,therefore, at the commencement of calibration or zero adjustment, theshaft must be brought to a stress-free condition, or the pre-stressedcondition must be included as fixed magnitude in the zero point. if wenow start from the fact that the shaft itself is in a state of freedomfrom stress, then in the measuring method employing strain gauges, thezero-point calibration can be undertaken in the static condition, i.e.with the shaft at rest. Calibration with strain gauges, however, isgenerally dependent upon stress and temperature, so that accuracy ofmeasurement can only be at tained with difiiculty over a large range.Generally, in zero point calibration, a so-called precompensation ofmeasuring errors to be found in the temperature expansion of theapparatus, is undertaken, so that then the actual zero is mreadydisplaced by a mean error. if, new, during the loaded state, themeasurement deviations do not occur the assumed order of magnitude ordirection, the strain gauge measuring method can then lead toconsiderable errors in indication.

if the measurement is based on the principle of the twisted shaft, andthe torque magnitudes are measured by means of a phase displacement,occurring through the mutual displacement of two pick-up toothed rims,there must be rotation of the rotor relative to the stator for anyindications to be obtained. For zero-point calibration, therefore, thetransmission shaft must normally be rotated and the speed must reach avalue dependent upon the transr -ission frequency. In normal shipsdrive, however, the requirement of so-called dynamic calibration can besatisfied in extremely few cases only, and a method is thereforedesirable for enabling zero calibration to be carried out in thephase-displacement measuring method but with the shaft stationary. Themethod described in the following indicates a technically satisfactoryway of doing this.

The basic principle of the method is as follows: the apparatus partacting as rotor in the working condition and rigidly connected to thetransmission shaft is used as stator in calibration method, while theapparatus part acting as stator in the normal working condition is nowused as rotor for zero-point calibration. In detail,

t, a the included in the line.

this is-efiected by the following device, shown in FIG- URE 10. The ring61, on which the magnet systems 62 are secured, is originally the statorpart of the measuring apparatus. A hollow cylinder 67 is formed integralwith the ring 61 and there is mounted on its external periphery two sliprings 63, to which the phase-separated voltages of the magnet systems 62can be transmitted by means of electric leads. A resilient wheel 64 runsagainst the inner surface 65 of the cylinder 67 in order to drive thelatter. An electric motor 66, mounted on a two part holder 66a to besecured to the transmission shaft, effects drive of the wheel 64 and thetransmission of the rotary movement to the part 67, 61 of the apparatus,which originally was the stator, but for zero adjustment is the rotor ofthe measuring apparatus. The electrical values are trans mitted to themeasuring instruments by means of brushes 63A engaging the slip rings.Since in the measuring method described, phase differences are used forthe measurements, slip-ring'transmission does not introduce anytransmission errors into the measurement itself, whereas if voltagedifierencesare to be measured, slip-ring transmission always gives riseto considerable transmission errors; From the standpoint of transmissionaccuracy, therefore, the slip-ring method can be used without objectionif, and this point is now important, after calibration by means of theslip rings, the line capacitance resulting fromthe slip-ringlength andthe slip-ring crosssectionis compensated by a capacitance member to beThe value of the transmission capacitance in the static zero-pointcalibration described above can be fixed, however, without difiiculty,and after zero-point calibration has been effected, the compensationcapacitance member can be incorporated in the transmission line or inthe measuring part.

In the example according to FIGURES 11 and 12, the driving mechanism isalso detachably mounted on the shaft by means ofa clamping holder 66a.The motor 65 drives the rim 67 of the stator by means of the resilientwheel 64. 'In other respects, this construction corresponds to theexample described in the foregoing.

If, for technical process reasons, the driving mechanism and the voltagetake-ofi device are to be mounted on the shaft while it is at restduring zero-point calibration, it is possible-to proceed in accordancewith the example shown in FIGURES '13 and 14. A vertically adjustableshear arrangement 72 is mounted-on a ground beam 71 so that by spindleadjustment-73, the supporting block 74 can be raised or lowered. Bymeans of this shear arrangement, it is now possible 'to support theground beam 71 positively against the shaft 75. A bracket 76, rotatableon the axis 76a, is coupled to the adjustable shears 72 so that thefriction wheel '77, mounted on the shaft of the driving motor 78, isbrought into frictional contact with the inner surface of the cylinderdisc 79.

In the pick-up constructions so far described, the main principle ofwhich consists in that the generation of the'voltagestakes placeinductively, an important question has been left unmentioned, namelythat of the optimum tooth-form of the pick-up Wheels. Extensivetheoretical and practical investigations have shown that the pick-upwheel, if it is'not to indicate any simulated phase displacements, mustfirst of all be free from pitch errors. This requirement for freedomfrom pitch errors is solved from the point of view of process techniquein modern gear-cutting machines, so that this basic requirement can beregarded as satisfied in construction. Much more difiicult from thepoint of view of manufacturing technique, however, 'is the secondrequirement of absolute circular'running of the toothed rim and theassociated constant depth of cut of the individual teeth of the pickupwheel. As soon, in fact, as the tooth parts fluctuate, in normallyprofiled tooth flanks, variations occur in the tooth tip width whichcause the magnetic flux formed between the magnet system-and tooth ofthe pick-up wheel to-undergo a phase displacement, produced by thevariable tip width of the tooth of the pick-up wheel. Since the relativedisplacements of the two toothed rims required for torque indication arein any event small, any variation in the tooth tip widths very soonfalsifies the measured result. This circumstance is counteracted byusing a tooth form in which the tooth flanks are planes parallel to oneanother,so that variation in the depth of cut of a tooth cannot produceany variation in the tooth tip width. The result is that with teeth freefrom pitch errors, the tooth tip widths remain constant, even in thecase of Variable tooth parts. Only such a configuration of the teethpermits transmission of the phase displacement of the two pick-up wheelsfree from error and independent'of mechanical effects.

I claim:

1. A pick-up for torque measuring apparatus, comprising a shaft, firstand second juxtaposed toothed rims in spaced relation co-axial with theshaft whereof the teeth are of equalpitch andare of magnetic material,first and second cylindrical support members surrounding the shaft andto which the first and second toothed rims,

respectively, are fixed, first and second fixing means secured tothefirst and second support members, respectively, and making substantialline contact with the shaft around first and second spaced peripherallines on the shaft, whereby the first and second rims will turn inaccordance with the turning of the shaft at said first and second lines,respectively, a stator adjacent the toothed rims, means connected to thestator for preventing it from rotating when a measurement is to he made,magnetic means in the stator for co-operating with the teeth for thegeneration of alternating current when the shaft turns, ball bearingsengaging the stator and one of the support members at spaced locationsdistributed around the entire circumference of said one support memberand supporting the stator in space and locating it both axially andradially with respect to said one support member, and eccentrics uponwhich the ball bearings are mounted and which are adapted to be turnedfor adjusting the positions of the bearings.

2. A pick-up for torque measuring apparatus, comprising a shaft, firstand second juxtaposed toothed rims in spaced relation co-axial with theshaftwhereof the teeth are of equal pitch and are of magnetic material,first and second cylindrical support members surrounding the shaft andto which the first and second toothed rims, respectively, are fixed,first and second fixing means secured'to the first and second supportmembers, respectively, and making substantial line contact with theshaft around first and second spaced peripheral lines on the shaft,whereby the first and second rims will turn in accordance with theturning of the shaft at said first and second lines, respectively, astator adjacent the toothed rims, means connected to the stator forpreventing it from rotating when a a measurement is to be made, magneticmeans in the stator for co-operating with the teeth for the generationof alternating current when the shaft turns, bearings engaging thestator and one of the support-members at spaced locations distributedaround the entire circumference of said one support member andsupporting the stator in space and locating itboth axially and radiallywith respect to said one support member, turnable eccentrics mounted ona first of the support members and ball bearings mounted on theeccentrics and engaging a,

bearing surface on the second support member, whereby said secondsupport member is supported with respect to said first support memberwhile being rotatable relative thereto.

3. A pick-up for torque measuring apparatus, comprising a shaft, firstand second juxtaposed toothed rims in spaced relation co-axial with theshaft whereof re teeth are of equal pitch and are of magnetic material,first and second cylindrical support members surrounding the shaft andto which the first and second toothed rims, respectively, are fixed,first and second fixing means secured to the first and second supportmembers, respectively, and making substantial line contact with theshafit around first and second spaced peripheral lines on the shaft,whereby the first and second rims will turn in accordance with theturning of the shafit at said first and second lines, respectively, astator adjacent the toothed rims, means connected to the stator forpreventing it from rotating when a measurement is to be made, a set ofmagnet systerns fixed to the stator for the generation of alternatingcurrent when the shaft turns, pole shoe-s of said magnet systemspresented to the teeth of one rim, a ring mounted in the stator forturning relative to the stator, another set of magnet systems secured tothe ring for the generation of alternating current when the shaft turns,pole shoes of those magnet systems presented to the teeth of the otherrim, the magnet systems of the two sets alternating at equal intervalsaround a circle centered on the shaft axis, and bearings engaging thestator and one of the support members at spaced locations distributedaround the entire circumference of said one support member andsupporting the stator in space and locating it both axially and radiallywith respect to said one support member.

4. A pick-up according to claim 3 and further comprising two furthermagnet systems fixed on the stator and each having a pole shoe, one shoebeing presented to the teeth of one rim and the other pole to the teethof the other rim.

5. A pick-up for torque measuring apparatus, comprising a shaft, firstand second juxtaposed toothed rims in spaced relation co-axial with theshaft whereof the teeth are of equal pitch and are of magnetic material,first and second cylindrical support members surrounding the shaft andto which the first and second toothed rims, respectively, are fixed,first and second fixing means secured to the first and second supportmembers, respectively, and making substantial line contact with theshaft around first and second spaced peripheral lines on the shaft,whereby the first and second rims will turn in accordance with theturning of the shaft at said first and second lines, respectively, astator adjacent the toothed rims, a fixed abutment member adjacent tothe stator, spring means effective between said abutment member and thestator for urging the stator towards the toothed rims, means connectedto the stator for preventing it from rotating when a measurement is to.be made, magnetic means in the stator for co-operating with the teethfor the generation of alternating current when the shaft turns, andbearings engaging the stator and one of the support members at spacedlocations distributed around the entire circumference of said onesupport member and supporting the stator in space and locating it bothaxially and radially with respect to said one support member.

6. A pick-up according to claim 5, wherein the spring means urge thestator as aforesaid in both the axial and the radial directions.

7. A pick-up according to claim 5, wherein the stator comprises acarriage in the shape of a segment of a circle, which carriage is urgedtowards the toothed rims by said spring means.

8. A pick-up according to claim 7 and further comprising means foradjusting the position of the carriage by turning it about the shafitaxis.

9. A pick-up according to claim 5, wherein the stator corn-prises aplurality of carriages in the shape of a segment of a circle equallyspaced around the shaft axis, which carriages are urged towards thetoothed rims by said spring means.

10. A pick-up according to claim 9, wherein the fixed abutment member isa ring which serves as an abutment for the spring means of all thecarriages and which is mounted for turning about the shaft axis.

11. A pick-up for torque measuring apparatus, comprising a shaft, firstand second juxtaposed toothed rims in spaced relation coaxial with theshaft whereof the teeth are of equal pitch and are of magnetic material,first and second cylindrical support members surrounding the shaft andto which the first and second toothed rims, respectively, are fixed,first and second fixing means secured to the first and second supportmembers, respectively, and making substantial line contact with theshafit around first and second spaced peripheral lines on the shaft,whereby the first and second rims will turn in accordance with theturning of the shaft at said first and second lines, respectively, astator adjacent the toothed rims, drive means connected to the statorfor turning the stator about the shaft axis while the shaft isstationary, means connected to the stator for preventing it fromrotating when a measurement is to be made, magnetic means in the statorfor co-operating with the teeth for the generation of alternatingcurrent when the shaft turns, slip rings and cooperating brushes forconveying from the stator alternating currents generated in the magneticmeans thereof, and bearings engaging the stator and one of the supportmembers at spaced locations distributed around the entire circumferenceof said one support member and supporting the stator inspace andlocating it both axially and radially with respect to said one sup portmember.

References Cited in the file of this patent UNITED STATES PATENTS2,217,539 De Bruin Oct. 8, 1940 2,270,760 Mershon Jan. 20, 19422,365,564 L-anger Dec. 19, 1944 2,579,629 Tubbs Dec. 25, 1951 2,675,700Van Degrift et a1 Apr. 20, 1954 2,754,683 Waugh July 17, 1956 2,766,617Tyler et al. Oct. 16, 1956 FOREIGN PATENTS 763,063 Great Britain Dec. 5,1956

1. A PICK-UP FOR TORQUE MEASURING APPARATUS, COMPRISING A SHAFT, FIRSTAND SECOND JUXTAPOSED TOOTHED RIMS IN SPACED RELATION CO-AXIAL WITH THESHAFT WHEREOF THE TEETH ARE OF EQUAL PITCH AND ARE OF MAGNETIC MATERIAL,FIRST AND SECOND CYLINDRICAL SUPPORT MEMBERS SURROUNDING THE SHAFT ANDTO WHICH THE FIRST AND SECOND TOOTHED RIMS, RESPECTIVELY, ARE FIXED,FIRST AND SECOND FIXING MEANS SECURED TO THE FIRST AND SECOND SUPPORTMEMBERS, RESPECTIVELY, AND MAKING SUBSTANTIAL LINE CONTACT WITH THESHAFT AROUND FIRST AND SECOND SPACED PERIPHERAL LINES ON THE SHAFT,WHEREBY THE FIRST AND SECOND RIMS WILL TURN IN ACCORDANCE WITH THETURNING OF THE SHAFT AT SAID FIRST AND SECOND LINES, RESPECTIVELY, ASTATOR ADJACENT THE TOOTHED RIMS, MEANS CONNECTED TO THE STATOR FORPREVENTING IT FROM ROTATING WHEN A MEASUREMENT IS TO BE MADE, MAGNETICMEANS IN THE STATOR FOR CO-OPERATING WITH THE TEETH FOR THE GENERATIONOF ALTERNATING CURRENT WHEN THE SHAFT TURNS, BALL BEARINGS ENGAGING THESTATOR AND ONE OF THE SUPPORT MEMBERS AT SPACED LOCATIONS DISTRIBUTEDAROUND THE ENTIRE CIRCUMFERENCE OF SAID ONE SUPPORT MEMBER ANDSUPPORTING THE STATOR IN SPACE AND LOCATING IT BOTH AXIALLY AND RADIALLYWITH RESPECT TO SAID ONE SUPPORT MEMBER, AND ECCENTRICS UPON WHICH THEBALL BEARINGS ARE MOUNTED AND WHICH ARE ADAPTED TO BE TURNED FORADJUSTING THE POSITIONS OF THE BEARINGS.